The present invention relates to generally an air bag system for protecting the passengers on an automotive vehicle in case of a collision, and more particularly a gas column type air bag which is a cushion device for an air bag system.
In the prior art gas column type air bag system, a plurality of elongated gas columns incorporated in an air bag are inflated with the high pressure gas supplied from a high pressure gas container which is opened in response to the signal from sensors for detecting the collision of the vehicle so that the normally folded air bag is expanded sucking the surrounding air therein, thereby restraining the occupant or passenger. The prior art air bag system of the type described has a distinct defect that the elongated gas columns tend to vibrate when inflated so that the expanded air bag may not be maintained in the desired shape. Another defect is that the time required for fully expanding the air bag is relatively longer so that the formation of the restraint for the occupant is delayed. When the length of the gas columns is made shorter in order to reduce the time required for fully expanding the air bag, the length of the air bag is also reduced too short to provide a sufficient restraint. When the cross sectional area of the gas columns is increased in order to minimize the vibration thereof, the quantity of the high pressure gas required for fully inflating them is inevitably increased with the result of the increase of volume of the high pressure gas container.
In order to prevent the bumping of the knees of the passenger against any part of the automotive body in case of a collision, the so-called knee bag or pad must be provided, but the incorporation of such knee bag or pad into the air bag makes the design of the air bag very complex and is therefore difficult in practice. Even when the knee bag or pad is incorporated, an increase in cost results. In case of the conventional air bag without gas columns of the type which is inflated by the high pressure gas directly flowing therein, the knee bag or pad may be readily provided, but the high pressure gas container with a large volume must be provided in order to supply the high pressure gas for inflating both the air bag and the knee pad. Furthermore, the inflation time becomes longer so that the restraint cannot be provided in time.